Return of blood to the heart is not facilitated by:

Correct Answer: D

Rationale: Venous valves prevent backflow, and the skeletal-muscle pump (contractions of skeletal muscles) aids venous return by compressing veins. Skeletal-muscle groups contribute to this pump. Venous pressure alone is low (near 0 mmHg at the venae cavae) and insufficient without these mechanisms.

Correct Answer: A

Rationale: Postoperative elevation in pulse and BP is typically due to the sympathetic nervous system’s response to stress (e.g., surgery), releasing catecholamines like epinephrine, increasing heart rate and vasoconstriction. The parasympathetic system slows heart rate, infection would take longer to manifest, and pain medications often lower BP.

Correct Answer: C

Rationale: Serum albumin, the most abundant plasma protein, maintains colloidal osmotic pressure (about 25 mmHg), keeping fluid in the bloodstream. Antibodies are from globulins, fibrinogen is a separate protein, and waste removal is primarily a kidney function.

Correct Answer: C

Rationale: Erythropoietin (EPO) production by the kidneys is triggered by hypoxia (e.g., hemorrhage, poor heart pumping, low oxygen). Epinephrine increases heart rate but doesn’t directly stimulate EPO.

Correct Answer: C

Rationale: There are 12 recognized clotting factors (I-XIII, missing VI) in the coagulation cascade, essential for normal clot formation, though not all are always active in every pathway.